Tropicman --
Just to bring things back to an even keel... regardless of water chemistry, this combination would be risky. Moray eels have the potential to be quite aggressive, and if kept in communities at all, they need to be kept with larger and fast-swimming things, such as scats and monos. Also, while Echidna spp. tend to be more or less predatory towards invertebrates only, Gymnothorax spp. view any fish in the tank as a potential meal. Morays are practically blind, and their approach to hunting is bite something, and then see if they can kill it. In the confines of an aquarium, this can prove very unpleasant for any other fishes in the tank.
Dragon gobies are relatively mild fish that work best when kept with smaller fish, such as guppies and mollies.
As for water chemistry. With moray eels, while there may be one or two species that spend (almost) all their lives in freshwater in the wild, in aquaria at least this doesn't seem workable. Almost always, the moray goes "off its food" after a few months, and then starves to death. You need at least SG 1.005, and ideally 1.010, to maintain them for any length of time.
If you want an "eel" for a tank with gobies, keep your eyes peeled for spaghetti eels (Moringua spp.). These are traded in the UK, just not frequently. The better stores (like Wildwoods) get them in, and most stores able to order fishes should be able to place a special order. They look like half-sized morays, but feed exclusively on mosquito larvae and similar. They are very hardy, and will do well at SG 1.005. They are also very peaceful, and actually work well in groups. All they demand is sand for burrowing in.
Cheers, Neale
Hey everyone my freshwater moray is coming this week and I was wondering if a dragon Goby would be a suitable tank mate the goby is around 6 inch and my moray which is coming is 20cm (supposidly) just a quick question would they live together
??